Hi Michael,

What do you think of the attached patch?

I think it fixes point 2 and 4 of bug#57395.  IMO point 3 (unsafe
non-root-owned file) is not really solvable in a remote setup: local and
remote uid can be any numbers.

What I'd like to do then is to work on point 1.  For this, my idea is to
make 'tramp-allow-unsafe-temporary-files' a three states variable with
the following possible values:

          - 'ask (default value): Prompt the user "Autosave file on
            local temporary directory, do you want to continue?"

          - nil: auto-save-mode should be disable on this file (same
            behaviour when answering "no" to the prompt)
            
          - t: auto-save-mode is on as usual (same behaviour when
            answering "yes" to the prompt)